The present invention relates to apparatus for use in conducting tests, particularly comparative tests, by a plurality of samples to be tested, and to a method of conducting a test on a plurality of samples.
Without prejudice to the generality of the invention it will be described hereinbelow with specific reference to its application to the performance of a test or assay on cell cultures, especially for the purpose of establishing the effects on the cells of various drugs and concentrations of drugs during an incubation period.
The apparatus of the present invention may be used in the assessment of, for example, the cytotoxic effect of drugs on both normal and tumorous cells. One known apparatus for processing a plurality of samples for subsequent assessment by a technique known as the Differential Staining Cytotoxicity (DiSC) assay is described in WO 89/06162; this apparatus comprises a plurality of separate tubes held in a first rack for incubation and a second rack for centrifugation. This apparatus has proved to be inconvenient since each tube first needs to be placed into the first rack during incubation of the sample in it and then needs to be moved to the second rack or holder for subsequent centrifuging in a cytocentrifuge (for example a Shandon Cytocentrifuge) or similar. There are a number of disadvantages to this known apparatus. A primary disadvantage lies in the fact that the tubes have to be made of a material to which the cells, particularly the tumour cells, are non adherent, or at least have a low adherence so that, upon centrifugation, release of the cells from the tube onto the microscope slide is reliably achieved without there being an unpredictable proportion of the cell population remaining within the tube. Typically, such tubes are made of polypropylene, which is not transparent, but merely translucent.